Propagation Of African Violet

There is no doubt that it is easy to propagate African violets, especially as there are several methods to increase successfully the number of plants from one. These methods are from a leaf, by a sucker or offset, by division and by seed.

Propagating from a leaf

All but one type of African violet propagate easily from leaves, although for greatest success the correct leaf must be selected. Thus the leaf must be mature and still have a good deal of potential growth in it; it is a mistake to take an old, nearly spent leaf from the outermost layer of leaves, because although it will produce plantlets it will take a long time to do so and they will not grow into such good mature plants. Nor should a young leaf from the centre of the crown be taken, as leaves do not achieve their full potential for propagation until they have grown to full size. Also its removal from the crown will spoil the shape of the plant. For rosette types, a leaf from the second or third layer of leaves from the outside would be the most appropriate. With trailing hybrids, a leaf from a similar layer on one of the branches should be removed for propagation.

The leaf is taken cleanly from the main stem of a rosette or the branch stem of a trailer by a sharp sideways tug so that no stub remains, as this could rot and infect the main stem. If a stub is left it should be removed as closely as possible to the stem. The leaf petiole should be trimmed to a length of 1.5in (4cm) and cleanly cut at a slanting angle using a sharp bladed knife or razor blade. The slanting cut is to expose a large area of tissue from which roots and plantlets will grow.

Sometimes one is given a leaf of a choice or rare hybrid, and its petiole is accidentally broken off at the base of the leaf blade. All is not lost, however, because a short stalk can be made by cutting away a small section of the leaf blade on either side of the main vein. This cut leaf may then be propagated following the normal method.

When propagating variegated hybrids, the leaf taken should have as much green color in it as possible. Even an all-green leaf from a variegate will produce variegated plantlets.

Rooting in compost

A leaf from a standard or large-sized plant should be potted one to a 2in (5cm) pot so that the minimum amount of moist compost may be used. With smaller sized plants it is best to pot two leaves back-to-back in a 2in (5cm) pot. The reason for this is so that roots can quickly fill the pot, thus allowing the plantlets to grow quickly. The pot should then be labeled with the name of the hybrid and the date of potting.
Some hybrids have very large leaves, and these would easily fall over if potted into small pots. These large leaves may be potted into a polystyrene cup that has had one side cut away to half its depth so that the leaf blade may be supported at its back by the remaining rim of the cup. It is unnecessary to use hormone rooting powder, as African violet leaves root quickly providing the correct one has been taken. The potted leaf should be put into a covered propagator or enclosed in a polythene bag, and placed in a warm, brightly lit position out of direct sunlight. If condensation builds up on the inside of the polythene bag it should be opened to allow the excess moisture to escape, and then closed again. Leaves will root just as easily when potted into small pots of moist vermiculite.

Rooting in water

African violet leaves may also be rooted in water using a dark-colored container such as a tablet bottle or a film cassette box of an appropriate size. Clear containers should be avoided, as the cut end of a leaf petiole will curl towards the brightest side of such a container. A small square of aluminum foil is secured over the top of the container after it is about three quarters filled with water. The trimmed base of the petiole is pushed thorough a central hole in the foil, and should be positioned so it is barely touching the water; it is therefore essential to top up the water level if evaporation occurs. It is not advisable to allow roots to grow longer than 0.5in (1cm) before potting the leaf into a small pot of compost, as longer roots are water roots and do not convert easily to compost roots. Leaves with water roots when potted into compost do not proceed quickly to plantlet production, in fact not until compost roots have grown; so the time spent producing those long water roots has in effect been wasted.

Growing on

Roots should have grown in six to eight weeks, and you can test if they have because then you will be able to lift the pot, leaf and compost all together by holding just the leaf tip in one's fingers. Plantlets should be starting to show above the compost in a further six to eight weeks, though this will depend upon the hybrid as some produce quickly whilst others can be very slow. At times a leaf is reluctant to put up plantlets and will itself grow larger; this sort may be encouraged to produce them by breaking off the upper half of its blade. The number of plantlets that a leaf produces can sometimes be amazing. On average the number is around four or five, although sometimes a leaf will produce only one, but there are hybrids that are extremely prolific, producing up to twenty and at times more. When this happens the heart must be hardened into discarding a percentage of them and potting up only the sturdiest. The wonder is that even after producing such a number the leaf can be retrimmed, potted, and will produce plantlets once again that are just as numerous and sturdy as the first crop.
When plantlets can be seen, and when watering is necessary, feeding should begin with a very weak dilution -say, at one-tenth strength -of a high nitrogen fertilizer such as fish emulsion. As the plantlets grow they should be hardened off by gradually removing the propagator top or opening the polythene bag daily for an hour or two, and be given a weak foliar feed. When they are 1.5 to 2in (4 to 5cm) tall and each have a minimum of four leaves, they are ready to be separated from their mother leaf and potted individually into 2in (5cm) pots, with the exception of variegated hybrids.
The potted plantlets should be stood in a tray lined with capillary matting that has been thoroughly wetted and then wrung out. Initially they are given a weak foliar feed to settle them into their new environment, and after about three weeks the feeding programme is changed to alternating a high nitrogen and a high phosphate fertilizer at one-eighth strength for every watering, with an occasional watering of plain tepid water.
When the roots of young standard or large-sized African violets have filled their pots, they are potted on into 2.5in (7cm) pots, given another foliar feed, then three weeks later the same feeding programme is followed as previously, using high nitrogen and high phosphate fertilizers. They may be left in this size pot until budding is initiated, when they should be potted on into 3.5in (9cm) pots. With miniature and semi miniature plants it is advisable not to pot on in the first instance but to repot into a clean pot of the same size, gently teasing away a little of the compost at the bottom of the root ball so that a small amount of fresh compost may be added.  The maximum size of pot for miniature and semi-miniature rosette hybrids is 2.5in (7cm) even when mature.
Odd Happenings - Do not be surprised to see a flower stalk grow from a young plantlet whilst it is still on its mother leaf. It may seem odd, but it happens sometimes and is not in the least detrimental.
Although the following happens infrequently from vegetative propagation, a plantlet may be produced that does not have the appearance of its parent or siblings in some way, either in leaf form or flower color and form. This is a mutant or sport and should be labeled as such. Further leaf propagation of this mutant should be carried out to ascertain whether or not it is stable, and if it proves to be so, then it should be labeled as 'Sport of. ..' and not given a new name.

Chimeras

This type of African violet poses a slight problem in its propagation because it does not come true to pattern by the normal leaf method. Plants grown from their leaves will rarely have flowers with the pinwheel pattern, but are more likely to have flowers of a solid color. To explain, chimera African violets have two genetically different tissues side by side, an outer and an inner layer in the petioles. Normally roots and plantlets grow from the inner tissue layer, therefore the original chimera is not produced because the outer tissue layer, which must be in the make-up of the propagated plant, is not in the plantlet.
There are certain leaves which may be used for propagation, namely the usually insignificant two small leaves behind the inflorescence on the flower peduncle. Flowers above these leaves should be removed so that very short pedicel stubs remain -but without damaging the base of the stubs -and the peduncle cut through about O.75in (2cm) below the tiny leaves. This cutting is inserted into a small pot of moist compost or vermiculite so that the leaf axils are level with the surface of the compost; it is then treated as a normal leaf cutting. Minute plantlets will grow from the axils of the two tiny leaves, and when large enough they should be potted up individually and grown on as any other plantlet.

Propagating from a sucker or offset

Sometimes a rosette type of African violet will produce a tiny sucker or offset in a leaf axil instead of a flower stalk. If allowed to continue to grow in this position, suckers will cause a plant to become multi-crowned. However, if the sucker is carefully eased away from the leaf axil when it has six to eight leaves, it may be used to grow into another plant. Care must be taken that no damage, or very little, is done to its rounded base when removing it.

A small pot is filled with moist compost, and a small hole made in the centre surface; this is filled with damp vermiculite into which the sucker base is inserted. As the vermiculite is sterile and without any food value, roots grow quickly and spread into the surrounding compost. The sucker should then be kept in a humid, warm and light position out of direct sunlight, and grown on as a plantlet.

The quickest way to propagate a trailing African violet to get a good-looking plant is by cutting off a short branch -which is actually an elongated sucker -just above a leaf node and rooting it down in a pot of compost and vermiculite as for a sucker. Because the base of the cutting is a stem without leaves, it is much less likely to suffer problems in rooting. Taking this cutting is also useful to the original plant, as its stem will then branch again.

The usual way of propagating chimera African violets so as to keep the true flower pinwheel pattern is by sucker growth. Plants can be induced to produce suckers from leaf axils either by carefully removing just the centre growing point, or by beheading the plant. The latter method gives a new plant quickly by being rooted down, and later suckers to increase the number. It needs some courage for a fairly new grower to behead a plant, but it is very worthwhile if chimeras need to be propagated. A word of warning, however: extra care must be taken that the base of a chimera sucker is not damaged in any way. A nice rounded sucker base can be obtained if you remove the leaf below it early on, thus allowing the sucker to spread out; then when it is of good size, a gentle sideways tug will take it cleanly away from the main stem of the old plant. Don't be too greedy: don't allow more than two suckers to grow on an old plant at a time; they will then be much better quality for growing on. When they are removed, others will probably grow from other leaf axils, and the old plant will not be so stressed as to stop growing.

Propagating from seed

African violet seed is dust-fine and requires very careful handling before being sown.

A small shallow pan such as a margarine tub, with drainage holes made in the bottom and a layer of perlite in it about O.5in (1cm) deep, is filled with fine moist compost. It is stood in a dish of warm water until the compost surface is seen to be thoroughly wet, when it is removed and allowed to drain for at least two hours. The seed is sown very thinly onto the compost; it should not be covered with more compost nor with fine vermiculite. Like all gesneriads, African violet seed needs light to germinate. The pan should be covered with clear plastic film to create a humid atmosphere for the seed, and either kept in a warm, light position out of direct sunlight, or placed under fluorescent lights. Alternatively, the uncovered pan may be placed in a heated, covered propagator running at 70°F (21°C). When the first sign of germination is apparent in three weeks or less, the pan should be taken from the propagator, covered with clear plastic film and placed on a window-sill out of direct sunlight or under fluorescent lights.

Do not start worrying if germination takes longer than three weeks. The time it takes can depend upon how fresh the seed is, although it has been known for seed as old as four years to germinate in six to eight weeks. But sometimes apparently fresh seed does not germinate because it is not viable. Always leave a seed pan for several months before giving up on the seed and discarding it.

As the seedlings grow, great care must be taken that the compost does not dry out; watering involves standing the pan in a dish holding 0.5in (1 cm) of tepid water for ten to fifteen minutes to allow the perlite in the bottom of the pan to soak up the water. Once the seedlings have four tiny leaves they may be pricked out into quarter-size seed trays of moist compost, and covered with clear plastic film. The exception to this is with the all-white seedlings growing from seed of variegates: it is pointless to prick these out because they will not grow any more as they lack chlorophyll. However, all-green seedlings, or those with only a little green in their leaves, will grow on to be variegates and should be pricked out. When necessary water should be given from the bottom by standing the seedlings in a dish, and a quarter-strength high nitrogen fertilizer should be given at every other watering.

Once the seedlings are established and have grown so they touch the plastic film, this should be removed gradually to harden them off. As they grow on and their leaves begin to touch each other, the time has come to transplant them into individual small pots -these should be of a suitable size, in particular so they are not over-potted and do not have too much compost for their roots. Keep them in a warm, humid atmosphere for a few days so that they can recover from the transplanting. The seedlings should now be fed with an eighth-strength balanced fertilizer at every watering and grown on to maturity. Long before this the all-green seedlings of variegates will be showing their full variegation potential.

Micro-propagation

Micro-propagation, or tissue culture, is a method used by commercial nurseries to produce very many plants of a hybrid in a comparatively short period of time. It is carried out in laboratories equipped with special facilities for controlled sterile conditions. It is not a propagation method that the average hobby grower at home is normally able to use.

The process entails a small section of an African violet leaf being cleaned and sterilized with chemicals, and then placed on an agar gel in a jar with a screw-down lid. The agar contains hormones and nutrients to induce shoot production, and within a week or two the leaf section will be covered with a multitude of shoots; it is then removed from the jar, divided and replaced in more sterile jars containing the same formula agar. Division continues until the number of shoots, which at this time do not have roots, is considered adequate for the required plant production. At this point all the shoots are transferred to sterile jars containing agar of a different formulation, this having hormones and nutrients that will promote root growth, and the shoots begin to grow roots. Sometimes roots have been known not to connect with a shoot, thus making the shoot useless. After about two months the agar is covered with a mass of minute plantlets which may then be teased apart into individual ones, pricked out into compost, and grown on into young plants under nursery conditions.

Comments

Post your comments, tips, or suggestions.